Once you've sprayed the plant, donít harvest any leaves for several days. And when you do, wash them well before using. Pyrethin, are also organic pesticides that will also work just fine. In mild infestations horticultural oil should suffice.
Root rot, is also sometimes a problem, in oregano. Be sure the soil is well drained, pick off any discolored or speckled foliage. The most common mistake gardeners make when growing Oregano is excessive moisture. Too much moisture, humidity, excessive rain, or over watering leads to root rot, which will surely lead the plants untimely demise.
To prevent this, you need a well drained soil with plenty of organic matter to ensure better drainage. Good air circulation is also essential to promote evaporation of surplus water, give the plants ample room to spread. Prune over-bearing foliage to promote air circulation. A light pebble mulch or gravel around the base of plants can also help keep the soil surface dry.
Oregano does well when planted near Pumpkin.
Keep it away from Marigolds as there is some indication marigolds will hamper their development.
Oregano repels Cucumber Beetles and some pests of Cabbage and related crops.
Harvest And Storage
You can begin harvesting oregano lightly when the plant reaches 8 inches in height. As with most herbs, the best time to harvest Oregano is just before it flowers in summer as its flavor is concentrated at this time.
For an abundant harvest, snip the stems just above the plantís lowest set of leaves, this will also encourage new growth for later cuttings. Oregano leaves can be dried, frozen, or refrigerated. Oregano is actually more intense when dried than it is fresh, drying deepens and enhances the flavor.
To Dry Oregano tie harvested stems and leaves together and hang them upside down in bunches in a dry, well-ventilated area. After drying, separate the leaves from stems and store in airtight containers.